Details disclosed in this section merely offers background information regarding embodiments of the present invention. No determination has been made, and no assertion is made, as to whether any of the below might be applicable as prior art with regard to the present invention.
With the remarkable development of a mobile communication network and related technologies, today's mobile communication devices have outgrown a typical category of simple communication devices or information providing devices and are now evolving into total entertainment devices.
In addition, a smart phone that combines the function of a communication terminal with that of a PDA (Personal Digital Assistant) is popularized in these days. A smart phone is an intelligent device in which computer-based functions such as internet communication and information retrieval are added to a mobile phone. Compared with a typical communication terminal, a smart phone has a higher-capacity memory and a higher-performance CPU (Central Processing Unit) and also uses an OS (Operating System) for supporting the execution of various applications, voice/data communication, interworking with PC (Personal Computer), and the like.
As one type of application techniques using a smart phone, a variety of location-based services (e.g., an in-vehicle navigator, a map viewer, a path finding, an indoor store guide, etc.) for offering convenience to users is launched and attracts much interest.
The important thing in location-based services is how to accurately identify or determine the location of a user.
Normally, for location tracking, a location-based service uses the GPS (Global Positioning System). However, the GPS is not available in indoor environments due to a failure in communication with satellites. Therefore, network-based location tracking techniques, e.g., based on RFID, Bluetooth, or Wi-Fi, are often used for indoor environments.
Cell-ID, triangulation, and fingerprint are well-known examples of such tracking techniques. In particular, fingerprint technique is to randomly select some positions in a service area and to estimate the location of a tracking target by using RSS (Received Signal Strength) collected at the selected positions.
This technique has an advantage of reducing environmental factors of a channel by collecting necessary information in advance. This technique, however, requires many referential positions for location tracking. Further, such a collection process is manually carried out by a service manager, and this causes a burden of time and cost.
Additionally, signal strength frequently varies depending on indoor space arrangement. Therefore, if a spatial arrangement is changed, the fingerprint should be measured again thereabout. Further, various causes of errors make it difficult to measure an exact location.